#include <iostream>
using namespace std;

// 定义一个加倍的内联函数
inline long DoubleNum(int inputNum)
{
	return inputNum * 2;
}


const double Pi = 3.1416;

// output parameter result 通过引用
void Area(double radius, double& result)
{
	result = Pi * radius * radius;
}

int main()
{
	double areaFetched = 0;
	Area(4, areaFetched);
	cout << areaFetched << endl;
	//
	// 调用内联函数
	cout << "Double is: " << DoubleNum(5) << endl;
	return 0;
}